Sorry for late response. I should have hurried. I just sent by my comment of your previous version's mail thread. Please look at it.
On Wed, Nov 28, 2012 at 11:48:30PM -0800, Nitin Gupta wrote: > Changelog v2 vs v1 > - None > > Adds zs_get_object_size(handle) which provides the size of > the given object. This is useful since the user (zram etc.) > now do not have to maintain object sizes separately, saving > on some metadata size (4b per page). > > The object handle encodes <page, offset> pair which currently points > to the start of the object. Now, the handle implicitly stores the size > information by pointing to the object's end instead. Since zsmalloc is > a slab based allocator, the start of the object can be easily determined > and the difference between the end offset encoded in the handle and the > start gives us the object size. > > Signed-off-by: Nitin Gupta <ngu...@vflare.org> > --- > drivers/staging/zsmalloc/zsmalloc-main.c | 177 > +++++++++++++++++++++--------- > drivers/staging/zsmalloc/zsmalloc.h | 1 + > 2 files changed, 127 insertions(+), 51 deletions(-) > > diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c > b/drivers/staging/zsmalloc/zsmalloc-main.c > index 09a9d35..65c9d3b 100644 > --- a/drivers/staging/zsmalloc/zsmalloc-main.c > +++ b/drivers/staging/zsmalloc/zsmalloc-main.c > @@ -112,20 +112,20 @@ > #define MAX_PHYSMEM_BITS 36 > #else /* !CONFIG_HIGHMEM64G */ > /* > - * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just > + * If this definition of MAX_PHYSMEM_BITS is used, OFFSET_BITS will just > * be PAGE_SHIFT > */ > #define MAX_PHYSMEM_BITS BITS_PER_LONG > #endif > #endif > #define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT) > -#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS) > -#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1) > +#define OFFSET_BITS (BITS_PER_LONG - _PFN_BITS) > +#define OFFSET_MASK ((_AC(1, UL) << OFFSET_BITS) - 1) > > #define MAX(a, b) ((a) >= (b) ? (a) : (b)) > /* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */ > #define ZS_MIN_ALLOC_SIZE \ > - MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS)) > + MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OFFSET_BITS)) > #define ZS_MAX_ALLOC_SIZE PAGE_SIZE > > /* > @@ -256,6 +256,11 @@ static int is_last_page(struct page *page) > return PagePrivate2(page); > } > > +static unsigned long get_page_index(struct page *page) > +{ > + return is_first_page(page) ? 0 : page->index; > +} > + > static void get_zspage_mapping(struct page *page, unsigned int *class_idx, > enum fullness_group *fullness) > { > @@ -433,39 +438,86 @@ static struct page *get_next_page(struct page *page) > return next; > } > > -/* Encode <page, obj_idx> as a single handle value */ > -static void *obj_location_to_handle(struct page *page, unsigned long obj_idx) > +static struct page *get_prev_page(struct page *page) > { > - unsigned long handle; > + struct page *prev, *first_page; > > - if (!page) { > - BUG_ON(obj_idx); > - return NULL; > - } > + first_page = get_first_page(page); > + if (page == first_page) > + prev = NULL; > + else if (page == (struct page *)first_page->private) > + prev = first_page; > + else > + prev = list_entry(page->lru.prev, struct page, lru); > > - handle = page_to_pfn(page) << OBJ_INDEX_BITS; > - handle |= (obj_idx & OBJ_INDEX_MASK); > + return prev; > > - return (void *)handle; > } > > -/* Decode <page, obj_idx> pair from the given object handle */ > -static void obj_handle_to_location(unsigned long handle, struct page **page, > - unsigned long *obj_idx) > +static void *encode_ptr(struct page *page, unsigned long offset) > { > - *page = pfn_to_page(handle >> OBJ_INDEX_BITS); > - *obj_idx = handle & OBJ_INDEX_MASK; > + unsigned long ptr; > + ptr = page_to_pfn(page) << OFFSET_BITS; > + ptr |= offset & OFFSET_MASK; > + return (void *)ptr; > +} > + > +static void decode_ptr(unsigned long ptr, struct page **page, > + unsigned int *offset) > +{ > + *page = pfn_to_page(ptr >> OFFSET_BITS); > + *offset = ptr & OFFSET_MASK; > +} > + > +static struct page *obj_handle_to_page(unsigned long handle) > +{ > + struct page *page; > + unsigned int offset; > + > + decode_ptr(handle, &page, &offset); > + if (offset < get_page_index(page)) > + page = get_prev_page(page); > + > + return page; > +} > + > +static unsigned int obj_handle_to_offset(unsigned long handle, > + unsigned int class_size) > +{ > + struct page *page; > + unsigned int offset; > + > + decode_ptr(handle, &page, &offset); > + if (offset < get_page_index(page)) > + offset = PAGE_SIZE - class_size + get_page_index(page); > + else > + offset = roundup(offset, class_size) - class_size; > + > + return offset; > } > > -static unsigned long obj_idx_to_offset(struct page *page, > - unsigned long obj_idx, int class_size) > +/* Encode <page, offset, size> as a single handle value */ > +static void *obj_location_to_handle(struct page *page, unsigned int offset, > + unsigned int size, unsigned int class_size) > { > - unsigned long off = 0; > + struct page *endpage; > + unsigned int endoffset; > > - if (!is_first_page(page)) > - off = page->index; > + if (!page) { > + BUG_ON(offset); > + return NULL; > + } > + BUG_ON(offset >= PAGE_SIZE); > + > + endpage = page; > + endoffset = offset + size - 1; > + if (endoffset >= PAGE_SIZE) { > + endpage = get_next_page(page); > + BUG_ON(!endpage); > + endoffset -= PAGE_SIZE; > + } > > - return off + obj_idx * class_size; > + return encode_ptr(endpage, endoffset); > } > > static void reset_page(struct page *page) > @@ -506,14 +558,13 @@ static void free_zspage(struct page *first_page) > /* Initialize a newly allocated zspage */ > static void init_zspage(struct page *first_page, struct size_class *class) > { > - unsigned long off = 0; > + unsigned long off = 0, next_off = 0; > struct page *page = first_page; > > BUG_ON(!is_first_page(first_page)); > while (page) { > struct page *next_page; > struct link_free *link; > - unsigned int i, objs_on_page; > > /* > * page->index stores offset of first object starting > @@ -526,14 +577,12 @@ static void init_zspage(struct page *first_page, struct > size_class *class) > > link = (struct link_free *)kmap_atomic(page) + > off / sizeof(*link); > - objs_on_page = (PAGE_SIZE - off) / class->size; > > - for (i = 1; i <= objs_on_page; i++) { > - off += class->size; > - if (off < PAGE_SIZE) { > - link->next = obj_location_to_handle(page, i); > - link += class->size / sizeof(*link); > - } > + next_off = off + class->size; > + while (next_off < PAGE_SIZE) { > + link->next = encode_ptr(page, next_off); > + link += class->size / sizeof(*link); > + next_off += class->size; > } > > /* > @@ -542,10 +591,11 @@ static void init_zspage(struct page *first_page, struct > size_class *class) > * page (if present) > */ > next_page = get_next_page(page); > - link->next = obj_location_to_handle(next_page, 0); > + next_off = next_page ? next_off - PAGE_SIZE : 0; > + link->next = encode_ptr(next_page, next_off); > kunmap_atomic(link); > page = next_page; > - off = (off + class->size) % PAGE_SIZE; > + off = next_off; > } > } > > @@ -596,7 +646,7 @@ static struct page *alloc_zspage(struct size_class > *class, gfp_t flags) > > init_zspage(first_page, class); > > - first_page->freelist = obj_location_to_handle(first_page, 0); > + first_page->freelist = encode_ptr(first_page, 0); > /* Maximum number of objects we can store in this zspage */ > first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size; > > @@ -871,7 +921,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size) > struct size_class *class; > > struct page *first_page, *m_page; > - unsigned long m_objidx, m_offset; > + unsigned int m_offset; > > if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE)) > return 0; > @@ -895,8 +945,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size) > } > > obj = (unsigned long)first_page->freelist; > - obj_handle_to_location(obj, &m_page, &m_objidx); > - m_offset = obj_idx_to_offset(m_page, m_objidx, class->size); > + decode_ptr(obj, &m_page, &m_offset); > > link = (struct link_free *)kmap_atomic(m_page) + > m_offset / sizeof(*link); > @@ -907,6 +956,9 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size) > first_page->inuse++; > /* Now move the zspage to another fullness group, if required */ > fix_fullness_group(pool, first_page); > + > + obj = (unsigned long)obj_location_to_handle(m_page, m_offset, > + size, class->size); > spin_unlock(&class->lock); > > return obj; > @@ -917,7 +969,7 @@ void zs_free(struct zs_pool *pool, unsigned long obj) > { > struct link_free *link; > struct page *first_page, *f_page; > - unsigned long f_objidx, f_offset; > + unsigned long f_offset; > > int class_idx; > struct size_class *class; > @@ -926,12 +978,12 @@ void zs_free(struct zs_pool *pool, unsigned long obj) > if (unlikely(!obj)) > return; > > - obj_handle_to_location(obj, &f_page, &f_objidx); > + f_page = obj_handle_to_page(obj); > first_page = get_first_page(f_page); > > get_zspage_mapping(first_page, &class_idx, &fullness); > class = &pool->size_class[class_idx]; > - f_offset = obj_idx_to_offset(f_page, f_objidx, class->size); > + f_offset = obj_handle_to_offset(obj, class->size); > > spin_lock(&class->lock); > > @@ -940,7 +992,7 @@ void zs_free(struct zs_pool *pool, unsigned long obj) > + f_offset); > link->next = first_page->freelist; > kunmap_atomic(link); > - first_page->freelist = (void *)obj; > + first_page->freelist = encode_ptr(f_page, f_offset); > > first_page->inuse--; > fullness = fix_fullness_group(pool, first_page); > @@ -970,10 +1022,10 @@ EXPORT_SYMBOL_GPL(zs_free); > * This function returns with preemption and page faults disabled. > */ > void *zs_map_object(struct zs_pool *pool, unsigned long handle, > - enum zs_mapmode mm) > + enum zs_mapmode mm) > { > struct page *page; > - unsigned long obj_idx, off; > + unsigned long off; > > unsigned int class_idx; > enum fullness_group fg; > @@ -990,10 +1042,10 @@ void *zs_map_object(struct zs_pool *pool, unsigned > long handle, > */ > BUG_ON(in_interrupt()); > > - obj_handle_to_location(handle, &page, &obj_idx); > + page = obj_handle_to_page(handle); > get_zspage_mapping(get_first_page(page), &class_idx, &fg); > class = &pool->size_class[class_idx]; > - off = obj_idx_to_offset(page, obj_idx, class->size); > + off = obj_handle_to_offset(handle, class->size); > > area = &get_cpu_var(zs_map_area); > area->vm_mm = mm; > @@ -1015,7 +1067,7 @@ EXPORT_SYMBOL_GPL(zs_map_object); > void zs_unmap_object(struct zs_pool *pool, unsigned long handle) > { > struct page *page; > - unsigned long obj_idx, off; > + unsigned long off; > > unsigned int class_idx; > enum fullness_group fg; > @@ -1024,10 +1076,10 @@ void zs_unmap_object(struct zs_pool *pool, unsigned > long handle) > > BUG_ON(!handle); > > - obj_handle_to_location(handle, &page, &obj_idx); > + page = obj_handle_to_page(handle); > get_zspage_mapping(get_first_page(page), &class_idx, &fg); > class = &pool->size_class[class_idx]; > - off = obj_idx_to_offset(page, obj_idx, class->size); > + off = obj_handle_to_offset(handle, class->size); > > area = &__get_cpu_var(zs_map_area); > if (off + class->size <= PAGE_SIZE) > @@ -1045,6 +1097,29 @@ void zs_unmap_object(struct zs_pool *pool, unsigned > long handle) > } > EXPORT_SYMBOL_GPL(zs_unmap_object); > > +size_t zs_get_object_size(struct zs_pool *pool, unsigned long handle) > +{ > + struct page *endpage; > + unsigned int endoffset, size; > + > + unsigned int class_idx; > + enum fullness_group fg; > + struct size_class *class; > + > + decode_ptr(handle, &endpage, &endoffset); > + get_zspage_mapping(endpage, &class_idx, &fg); > + class = &pool->size_class[class_idx]; > + > + size = endoffset + 1; > + if (endoffset < get_page_index(endpage)) > + size += class->size - get_page_index(endpage); > + else > + size -= rounddown(endoffset, class->size); > + > + return size; > +} > +EXPORT_SYMBOL_GPL(zs_get_object_size); > + > u64 zs_get_total_size_bytes(struct zs_pool *pool) > { > int i; > diff --git a/drivers/staging/zsmalloc/zsmalloc.h > b/drivers/staging/zsmalloc/zsmalloc.h > index de2e8bf..2830fdf 100644 > --- a/drivers/staging/zsmalloc/zsmalloc.h > +++ b/drivers/staging/zsmalloc/zsmalloc.h > @@ -38,6 +38,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long > handle, > enum zs_mapmode mm); > void zs_unmap_object(struct zs_pool *pool, unsigned long handle); > > +size_t zs_get_object_size(struct zs_pool *pool, unsigned long handle); > u64 zs_get_total_size_bytes(struct zs_pool *pool); > > #endif > -- > 1.7.10.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/